Why should I know my weight and waist size?

A waist measuring tape

Senior Cardiac Nurse Emily Reeve talks to BHF Associate Medical Director Dr Mike Knapton about why it’s important to know your real size. 

Which numbers should I know?

Weight on its own doesn’t tell us a lot, as a healthy tall person will generally weigh more than a healthy short person. This is why we use a measurement called body mass index (BMI). This is your weight (in kilos) divided by the square of your height (in metres). While this calculation isn’t perfect (it can give a misleading result for people with lots of muscle mass and pregnant women, for example), it can be a quick and useful guide to help assess whether someone is within their healthy weight range and, if not, how far outside it they are.

Another useful measurement is your waist circumference. This is important because your body shape can affect your risk of heart and circulatory disease. Visceral fat, which is stored around your abdominal organs and increases your waist size, is linked to an increased risk of heart and circulatory disease – more so than fat that is stored around the hips and thighs.

Why should I know my BMI and waist circumference?

Your weight and body shape can make a real difference to your risk of heart disease. Obesity increases your risk of conditions that put you at risk of heart and circulatory disease and conditions, such as high blood pressure and type 2 diabetes.

Carrying extra weight puts increased strain on the joints

Your weight can also raise your risk of many types of cancer, such as bowel, womb, oesophagus, pancreas and some breast cancers. In fact, one in 20 cancers in the UK are linked to being overweight or obese.

Carrying extra weight puts increased strain on the joints, so there’s an increased risk of joint problems and osteoarthritis, as well as worsening arthritis if you already have it.

What should my numbers be?

If you know your height and weight, you can calculate your own BMI. Online calculators allow you to put in your height and weight in either imperial or metric (use the same for both measurements). You can use our BMI calculator.

Depending on the result, this will put you into one of four groups:

  • Low weight/malnourished (BMI below 18.5)
  • Normal weight (18.5–25)
  • Overweight (25.1–30)
  • Obese (over 30).

You can see if you are in a higher risk category, and then use BMI to calculate a target weight and monitor progress towards this over time.

For your waist circumference you just need a tape measure (like the one received in your Heart Matters welcome pack). Measure your waist at the mid-point between the bottom of your ribs and the top of your hips. For European women this should be no more than 88cm (35in) and for European men no more than 102cm (40in). People of African Caribbean, Black African or South Asian heritage should have a circumference of no more than 80cm (32in) for women and 90cm (35.5in) for men, as studies show they are at risk with a lower waist measurement than white European people.

Find out more

We’ve got lots of resources to help you manage your weight. These include our free booklet Facts not fads: your guide to healthy weight loss.

You can also read our food articles, or check out our heart-healthy recipes

More useful information